The present invention relates to a system for correcting a time base error of an information reproducing apparatus, especially of a video disc player.
In an information reproducing apparatus, for example, a video disc player, several servo systems are used for obtaining reproducing information for reproducing high quality pictures, for example. A first servo system is an auto focus servo system which drives an object lens for focusing a light beam emitted from a laser light source onto a disc surface of a video disc. A second servo system is a tracking tracking servo system which moves the object lens in a radial direction of the disc for maintaining a focused light spot to impinge on an information track recorded on the video disc. A third servo system is a time base correcting system which is a so called jitter servo system. An example of the jitter servo system is shown in FIG. 11 and described in U.S. Pat. No. 4,371,899. The jitter servo system controls a rotational speed of a spindle motor rotating the disc, or moves the object lens in a tangential direction of the track for reproducing the information recorded on the disc surface in synchronism with a prescribed synchronizing signal.
It is known and described in U.S. Pat. No. 4,415,935 to use a trapezoidal waveform signal for correcting a phase difference between the reproduced signal and a reference signal. However, this patent does not take into considerations the fluctuation of a DC offset included in the phase difference error signals.
Additionally, in the prior arrangements, the control of the phase difference and the control of the rotational speed of the spindle motor has been effected by independent control systems, respectively.